The Impact of the Incidence of Diabetic Complications on Mortality in Colorectal Cancer Patients with Diabetes: A Nationwide Study

Purpose: The prevalence of diabetes is higher in patients with colorectal cancer, which is important because diabetes is recognized as a risk factor for increased mortality. This study investigated the impact of incident diabetes-related complications on all-cause five-year mortality in older aged colorectal cancer patients with diabetes.

Methods: The 2008 to 2019 National Health Insurance Service data on the elderly were used to identify patients with colorectal cancer aged 60 years or above diagnosed with type 2 diabetes mellitus. The outcome measure was all-cause five-year mortality. The main independent variable was incident status of diabetes-related complications using the Diabetes Complications Severity Index (DCSI). Survival analyses were performed using the Cox proportional hazards model, in addition to the calculation of risk differences. Subgroup analysis was conducted based on the type of complication and DCSI scores.

Results: Among 1,312 individuals, 319 (24.3%) died within five years after one year of a cancer diagnosis. The risk of mortality was higher in patients with diabetes and cancer having incident diabetes-related complications (Hazard Ratio 1.29, 95% Confidence Interval 1.03-1.63). These tendencies were generally maintained regardless of the type of complication and DCSI scores.

Conclusion: The incidence of diabetes-related complications after cancer diagnosis was associated with an increased risk of all-cause five-year mortality in older patients with colorectal cancer and preexisting diabetes.